"If Donald Trump continues to do well and sort of stays on the path he's on, I think he'll be the nominee," said Santorum. "If he doesn't, then things are going to get complicated."

Santorum pointed out the possibility that delegates at the convention could choose a nominee that is not in the race. He said he was not endorsing any current candidate, but he would support the eventual Republican nominee.

He also said he would do his part to help the eventual nominee win.

Santorum dropped out of the 2016 presidential race after he won less than 1 percent of voters in the Feb. 1 Iowa caucus — he won that caucus in the 2012 primary.

After he exited the race, Santorum supported Marco Rubio's presidential campaign. In an interview reported by Politico, Santorum was unable to name any accomplishments that Rubio had made during his Senate career.

In March, Santorum spoke at the Georgetown Institute of Politics and Public Service. There, he said if liberal culture gets more of a foothold in the U.S., "this place will die and become just like Europe," reported The Hoya.